Core Power

Understanding HIIT and Its Benefits

By Mathew Forzaglia

Mathew Forzaglia is a top digital fitness professional and fitness trainer from New York City. He is the founder of Forzag Fitness, a high-intensity, functional workout that can be streamed worldwide. By bringing personalized attention to a wide audience – anywhere, anytime – he is changing the game in digital fitness. Mathew is certified by several nationally accredited organizations which have given him a breadth of knowledge and experience.


HIIT or High-Intensity Interval Training is a set of intervals alternating between high-intensity exercise and low or medium intensity level intervals. The idea is that you want to work at a maximum level of effort and then pull back, resting for a short recovery, before you go back into that maximum level interval again. HIIT can be done a vast amount of ways from the exercises or equipment you use to the ratio of intervals and duration. There is no right or wrong, but you want to make sure the intervals make sense.

The Benefits of HIIT Training

Because you are pushing your body to work at such a high level of intensity during the working intervals, you can actually burn a lot of calories in a shorter amount of time. HIIT workouts raise your metabolic rate even after you’re done working out. This is because HIIT workouts elevate your resting heart rate while using energy to recover your body after a workout. This can happen for up to 24 hours after the workout.

What’s the difference between HIIT (High-Intensity Interval Training) and LISS (Low-Intensity Steady State)?

During HIIT workouts, we are aiming for upwards to 80-90% max heart rate for a short period of time. HIIT is an anaerobic activity. This means your body uses stored glucose in the muscles without relying too much on oxygen. During HIIT intervals, your oxygen demand is greater than the oxygen supply, so your body has to release energy without oxygen. You will feel tired faster due to the response of your body releasing lactic acid. Think of it like doing repeats of sprints.

Steady-state or LISS (low-intensity steady state) cardio is an aerobic activity. In a steady-state activity, you use around 50-60% of your max heart rate for about 45 minutes. This means the body relies on oxygen to release energy. The energy release is moderate and steady over a long duration. Think of long-distance running where you can hold a conversation.

A lot of people tell me, “I don’t have time to work out!”

This is one of my favorite benefits of HIIT training for many reasons. You can go ahead and toss that old excuse of, “I don’t have time to work out.” HIIT can be done in 30 minutes or less, and you still get more of an effective workout than going to the gym for an hour. An added bonus is that you don’t need any equipment, and it can be done anywhere!

Want an improved body composition?

Because HIIT is more of an anaerobic-style workout, it will change your body composition by targeting your muscles. HIIT workouts build lean muscle and burn fat. LISS cardio is an aerobic-style workout; therefore, it tends to target your cardiovascular system and can burn up your muscle mass.

How many days a week can we HIIT it?

It is recommended that you do HIIT workouts 2-4 times a week. Since you are working at such high intensity for a short amount of time, you are putting a greater demand on the body. Even though they are short intervals, you still need to recover before going into the next workout.

Is HIIT for everyone?

No, just like spicy foods are not for everyone either. If you’re more of a beginner, you may want to start with HIIT workouts 2 times per week and work your way up. If you are a seasoned individual with a busy life, then maybe you can do HIIT workouts 5 days a week. No matter what – it is effective and efficient for everybody. Even if you have an injury, you can still do low impact style HIIT workouts, whether that is walking, rowing, or biking. While everyone has different needs and different goals, I always say “try it before you knock it.” HIIT workouts might just be the missing component that leads you closer to your goals.

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